This is not the review that will tell you to avoid a Jessica Chastain movie. Chastain’s take-no-prisoners, full-throttle performances are a pleasure in themselves, and she is at a stage of her career where she can do no wrong. Somewhere in the next world, Joan Crawford and Bette Davis are actually agreeing on something, and it’s that they really, really like Jessica Chastain.

So thinking of it this way, as a Chastain vehicle, “Molly’s Game” is not bad at all. It allows her to be strong and forthright, to play surface amorality and inner moral fortitude, while doing as many flattering costume changes as she can cram in.

But “Molly’s Game” aspires to be more than that. Thus, writer/director Aaron Sorkin takes a sordid, morally muddled anecdote and inflates it with an importance it doesn’t deserve and can’t sustain.

The movie tells the fact-based story of the real-life Molly Bloom, a young woman from a middle-class background, whose parents wanted her to become a lawyer, but she wanted adventure. She was an Olympic-level skier, but an injury ended her career.

When we first meet her, she is being arrested by a team of FBI agents who are pointing machine guns at her and showing her a piece of paper that says “the people of the United States versus Molly Bloom.” When you get all the people of the United States mad at you at once, that’s never a good thing.

In flashback, with a liberal use of voice-over, we get the story. Instead of going to law school, young Molly moves to Los Angeles. She becomes the assistant to a guy running a high-stakes poker game involving various (unnamed) celebrities, business and underworld figures. Because her boss is a nasty guy, and because she is smarter than he is, she takes over the game and moves it from a dark club to a luxury hotel suite.

We end up finding out more about poker games than we want to know, but some of the information is interesting. Apparently, it’s not illegal — or sort of not illegal — to host a poker game. But if you skim a small percentage off the top, Uncle Sam takes offense. That’s the source of Molly’s legal troubles.

In between flashback scenes showing her expanding poker empire, we get many scenes of Molly conferring with her lawyer, played by Idris Elba; and this is where Sorkin reveals his weakness as a first-time director. He uses arguments for exposition and rapid-fire banter to explain arcane particulars of the poker world. Yet at least half the time, it’s impossible to follow what they’re talking about. Sorkin’s default, when in doubt, is to steamroll the audience with dialogue. A more experienced director wouldn’t do that.

Chastain’s alert intelligence goes a long way toward making us believe in Molly, but it can’t go all the way because Molly keeps doing stupid things. For example, do you really need to be Einstein to realize that maybe bringing your multimillion-dollar poker game to New York City might occasion a visit from a 250-pound guy named Vinny?

In her previous film, “The Zookeeper’s Wife,” Chastain played a real-life woman in Poland who spent years risking her life to save hundreds of Polish Jews during World War II. At any point, she could have been denounced and killed by the Nazis. That’s a memorable character.

“Molly’s Game,” on the other hand, is a 140-minute epic about a somewhat clueless but by no means awful woman who, for a time, figures out a way to make a living off degenerate gamblers. Good for her, but is there anything here that is worth 140 minutes of our time?

Molly’s father is played by Kevin Costner — it doesn’t get much better than that. But the demiworld of poker is of limited interest; just people sitting around a table. Likewise, the internal crisis — the spectacle of Molly experiencing ever-increasing stress — has little impact, because it’s a stress she can walk away from. It’s not as though she just became prime minister and the Germans are about to bomb London.

At a certain point, everyone watching “Molly’s Game” will wonder, “Why should I care about any of this?” It’s a question Sorkin should have anticipated. He has no good answer.